Quiz statistics report doesn't show chosen random questions

The quiz statistics report no longer shows the chosen questions for a random question slot when generating the table summary.

The table should show the list of questions that were chosen for a random question slot in the quiz attempts (where the number of distinct questions allocated is < 9).

To replicate:

1. Log in as admin
2. Enrol 2 users as students
3. Create and view a quiz
4. Go to the question bank (edit cog > question bank)
5. Create 5 questions in the default category for the course (it doesn't matter the type of question but I find true/false the easiest because you'll need to attempt the quiz).
6. Edit the quiz and add a random question from the default course category
7. Log in as each of the students and attempt the quiz
8. Log in as admin
9. View the quiz
10. View the statistics report (edit cog > results > statistics)
11. You should see a row (Q# will likely be 1) for the random question slot
12. You should see some rows below that for each of the questions that were allocated during the attempts above (Q# will likely be 1.1, 1.2, 1.3... etc).

This is how the report should look:

This is how it looks with the bug: